The services of ecological systems and the natural capital stocks that produce them are critical to the functioning of the Earth's life-support system. They contribute to human welfare, both directly and indirectly, and therefore represent part of the total economic value of the planet. We have estimated the current economic value of 17 ecosystem services for 16 biomes, based on published studies and a few original calculations. For the entire biosphere, the value (most of which is outside the market) is estimated to be in the range of US$16-54 trillion (10^(12)) per year, with an average of US$33 trillion per year. Because of the nature of the uncertainties, this must be considered a minimum estimate. Global gross national product total is around US$18 trillion per year.

https://www.esd.ornl.gov/benefits_conference/nature_paper.pdf

The value of the world's ecosystem services and natural capital

http://people.uncw.edu/pawlikj/2008AquatBotNagle.pdf

The habitat function of mangroves for terrestrial and marine fauna: a review

Chesapeake Bay has been the subject of intensive research on cultural eutrophication and extensive efforts to reduce nutrient inputs. In 1987 a commitment was made to reduce controllable sources of nitrogen (N) and phosphorous (P) by 40% by the year 2000, although the causes and effects of eutrophication were incompletely known. Subsequent research, modeling, and monitoring have shown that: (i) the estuarine ecosystem had been substantially altered by increased loadings of N and P of approximately 7- and 18-fold, respectively; (ii) hypoxia substantially increased since the 1950s; (iii) eutrophication was the major cause of reductions in submerged vegetation; and (iv) reducing nutrient sources by 40% would improve water quality, but less than originally thought. Strong public support and political commitment have allowed the Chesapeake Bay Program to reduce nutrient inputs, particularly from point sources, by 58% for P and 28% for N. However, reductions of nonpoint sources of P and N were projected by models to reach only 19% and 15%, respectively, of controllable loadings. The lack of reductions in nutrient concentrations in some streams and tidal waters and field research suggest that soil conservation-based management strategies are less effective than assumed. In 1997, isolated outbreaks of the toxic dinoflagellate Pfiesteria piscicida brought attention to the land application of poultry manure as a contributing factor to elevated soil P and ground water N concentrations. In addition to developing more effective agricultural practices, emerging issues include linking eutrophication and living resources, reducing atmospheric sources of N, enhancing nutrient sinks, controlling sprawling suburban development, and predicting and preventing harmful algal blooms.

/pdf/chesapeake-bay-eutrophication-scientific-understanding-57pxkb4mp1.pdf

Chesapeake Bay Eutrophication: Scientific Understanding, Ecosystem Restoration, and Challenges for Agriculture

. Estuaries are biogeochemical hot spots because they receive large inputs of nutrients and organic carbon from land and oceans to support high rates of metabolism and primary production. We synthesize published rates of annual phytoplankton primary production (APPP) in marine ecosystems influenced by connectivity to land – estuaries, bays, lagoons, fjords and inland seas. Review of the scientific literature produced a compilation of 1148 values of APPP derived from monthly incubation assays to measure carbon assimilation or oxygen production. The median value of median APPP measurements in 131 ecosystems is 185 and the mean is 252 g C m−2 yr−1, but the range is large: from −105 (net pelagic production in the Scheldt Estuary) to 1890 g C m−2 yr−1 (net phytoplankton production in Tamagawa Estuary). APPP varies up to 10-fold within ecosystems and 5-fold from year to year (but we only found eight APPP series longer than a decade so our knowledge of decadal-scale variability is limited). We use studies of individual places to build a conceptual model that integrates the mechanisms generating this large variability: nutrient supply, light limitation by turbidity, grazing by consumers, and physical processes (river inflow, ocean exchange, and inputs of heat, light and wind energy). We consider method as another source of variability because the compilation includes values derived from widely differing protocols. A simulation model shows that different methods reported in the literature can yield up to 3-fold variability depending on incubation protocols and methods for integrating measured rates over time and depth. Although attempts have been made to upscale measures of estuarine-coastal APPP, the empirical record is inadequate for yielding reliable global estimates. The record is deficient in three ways. First, it is highly biased by the large number of measurements made in northern Europe (particularly the Baltic region) and North America. Of the 1148 reported values of APPP, 958 come from sites between 30 and 60° N; we found only 36 for sites south of 20° N. Second, of the 131 ecosystems where APPP has been reported, 37% are based on measurements at only one location during 1 year. The accuracy of these values is unknown but probably low, given the large interannual and spatial variability within ecosystems. Finally, global assessments are confounded by measurements that are not intercomparable because they were made with different methods. Phytoplankton primary production along the continental margins is tightly linked to variability of water quality, biogeochemical processes including ocean–atmosphere CO2 exchange, and production at higher trophic levels including species we harvest as food. The empirical record has deficiencies that preclude reliable global assessment of this key Earth system process. We face two grand challenges to resolve these deficiencies: (1) organize and fund an international effort to use a common method and measure APPP regularly across a network of coastal sites that are globally representative and sustained over time, and (2) integrate data into a unifying model to explain the wide range of variability across ecosystems and to project responses of APPP to regional manifestations of global change as it continues to unfold.

/pdf/phytoplankton-primary-production-in-the-world-s-estuarine-181r8owda9.pdf

Phytoplankton primary production in the world's estuarine-coastal ecosystems

Estuaries and coastal wetlands are critical transition zones (CTZs) that link land, freshwater habitats, and the sea. CTZs provide essential ecological functions, including decomposition, nutrient cycling, and nutrient production, as well as regulation of fluxes of nutrients, water, particles, and organisms to and from land, rivers, and the ocean. Sediment-associated biota are integral to these functions. Functional groups considered essential to CTZ processes include heterotrophic bacteria and fungi, as well as many benthic invertebrates. Key invertebrate functions include shredding, which breaks down and recycles organic matter; suspension feeding, which collects and transports sediments across the sediment–water interface; and bioturbating, which moves sediment into or out of the seabed. In addition, macrophytes regulate many aspects of nutrient, particle, and organism dynamics above- and belowground. Animals moving within or through CTZs are vectors that transport nutrients and organic matter across terrestrial, freshwater, and marine interfaces. Significant threats to biodiversity within CTZs are posed by anthropogenic influences; eutrophication, nonnutrient pollutants, species invasions, overfishing, habitat alteration, and climate change affect species richness or composition in many coastal environments. Because biotic diversity in marine CTZ sediments is inherently low whereas their functional significance is great, shifts in diversity are likely to be particularly important. Species introductions (from invasion) or loss (from overfishing or habitat alteration) provide evidence that single-species changes can have overt, sweeping effects on CTZ structure and function. Certain species may be critically important to the maintenance of ecosystem functions in CTZs even though at present there is limited empirical evidence that the number of species in CTZ sediments is critical. We hypothesized that diversity is indeed important to ecosystem function in marine CTZs because high diversity maintains positive interactions among species (facilitation and mutualism), promoting stability and resistance to invasion or other forms of disturbance. The complexity of interactions among species and feedbacks with ecosystem functions suggests that comparative (mensurative) and manipulative approaches will be required to elucidate the role of diversity in sustaining CTZ functions.

http://levin.ucsd.edu/publications/Ecosystems2001%20Levin%20et%20al.pdf

The Function of Marine Critical Transition Zones and the Importance of Sediment Biodiversity

Trends in global and United States fish catches were examined to determine the status of estuarine fisheries yields relative to those from other ecosystems. Potential marine fish production, based upon primary production relationships, was estimated globally and for specific marine ecosystems, including estuaries. While global fish catches increased substantially during the past two decades and continued to increase through 1989, catches of estuarine-dependent species have peaked or stabilized. In the United States, total catches have increased but many estuarine-dependent fisheries have declined, although the declines in catches are no more dramatic than those of heavily-fished continental shelf species. Overfishing probably is the primary cause of declines in estuarine and shelf fisheries. A few estuarine-dependent species of the United States have experienced substantial increases in harvests since 1970, for example, Pacific salmons, menhaden, and penaeid shrimps. The percentage contribution of major estuarine fisheries to the United States commercial catch declined between 1970 and 1990, although the yield of these species increased substantially. Global marine fisheries production at trophic level 2.5 was estimated to be 1,359 million tons. Potential yield was estimated to be 307 million tons, but the 1989 world marine catch was only 86.5 million tons. The major fraction, 196 million tons, of the estimated potential yeild was for the open ocean where technological constraints may prevent its full realization. Of the remaining 111 million tons of the potential, 18.0 million tons (16.2%) may come from estuaries and probably already is fully exploited. The potential catches from shelves, 68.5 million tons (61.6%), and upwelling areas, 24.8 million tons (22.2%), while considerably larger than those from estuaries, are lower in a relative sense (per unit area) than fisheries production and potential catch in estuarine zones. Relationships between fish production, fish harvest, and primary production were examined in specific estuaries. The developing role of aquaculture and its effect on estuarine fisheries are discussed.

Recent trends in estuarine fisheries: Predictions of fish production and yield

An individual-based model of the population dynamics of young-of-the-year striped bass Morone saxatilis in the Potomac River, Maryland, was used to test the hypothesis that historically high recruitment variability can be explained by changes in environmental and biological factors that result in relatively small changes in growth and mortality rates of striped bass larvae The four factors examined were (1) size distribution of female parents, (2) zooplankton prey density during the development of striped bass larvae, (3) density of competing larval white perch M americana, and (4) temperature during larval development Simulation results suggest that variations in female size and in prey for larvae alone could cause 10-fold variability in recruitment But no single factor alone caused changes in vital rates of age-0 fish that could account for the 145-fold variability in the Potomac River index of juvenile recruitment However, combined positive or negative effects of two or more factors resul

Individual‐Based Model of Young‐of‐the‐Year Striped Bass Population Dynamics. II. Factors Affecting Recruitment in the Potomac River, Maryland

In this report we develop age-length keys and derive age-frequency data. We estimate striped bass and white perch mortality and growth rates, based on the otolith-aging analysis. We also report on hatch-date frequencies of striped bass and white perch larvae, and we discuss environmental effects on recruitment potential.

Edward S. Rutherford

Papers

Recent trends in estuarine fisheries: Predictions of fish production and yield

Individual‐Based Model of Young‐of‐the‐Year Striped Bass Population Dynamics. II. Factors Affecting Recruitment in the Potomac River, Maryland

Mortality, growth and growth rate variability of striped bass larvae in Chesapeake Subestuaries